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Recent research conducted by NIOSH, Pittsburgh Research Laboratory showed that electrical current levels permitted under parent regulations may not limit cable temperatures to less than 90 °C in reeled trailing cables. Reeled cables, tightly wrapped with many turns, ell carrying current in an enclosed space, can become overheated due to poor heat transfer. This overheating can cause the cable insulation to soften and become easily damaged. The damaged insulation reduces the life of the cable and can lead to shock, electrocution, and mine foes. This paper describes a method of measuring the conductor temperature of untie trailing cables during no anal operation. The temperature is measured using a 50/175 micrometer Graded Index Multimode Optical Fiber located in the center of the metallic conductors. Distributed temperature measurements arc made using an Optical Time Domain Reflectometer (OTDR). This system is capable of measuring temperature with an accuracy of plus or minus one degree centigrade over a length of 4 km at 1-m intervals. With this unique way of measuring temperature, tests can be conducted simulating actual mine conditions and provide important data to allow MSHA's Approval and Certification Center to develop approval criteria for cyclically rated reeled machines.

Overheating of electric cables on shuttle cars has long been recognized as a cause of premature insulation failure leading to shock and electrocution. Use of cable reels on shuttle cars can cause excessive heat build up which, in turn, causes the cab...

"Reports of Investigations (RIs) present the results of original mining health and safety research. They describe individual, short-term studies and include the objective of the research, the materials and techniques used, and the results of tests or...

National Institute for Occupational Safety and Health. National Institute for Occupational Safety and Health.

Published:

1999

Series:

DHHS publication ; no. (NIOSH) 99-102

Description:

"Reports of Investigations (RIs) present the results of original mining health and safety research. They describe individual, short-term studies and include the objective of the research, the materials and techniques used, and the results of tests or...

"This U.S. Bureau of Mines report describes the development, system- by-system evaluation, and preliminary surface testing of a flywheel- powered shuttle car. The use of a self-contained flywheel power source has the potential to eliminate the numero...